Protective ferrule for heat exchanger tubes



June 19', 1951 v PEN ELLA 2,557,360

' PROTECTIVE FERRULE FOR HEAT EXCHANGER TUBES Filed April 5, 1948 SAMUEL PENNELLA JNVENTOR.

OFFICE PROTECTIVE FERRULE FOR HEAT EXCHANGER TUBES Samuel Pennella, Pcmpton Lakes, N. 5. Application April 5, 1948, Serial No. 18,937

2 Claims. (Cl. 285-56) This invention relates to heat exchangers such use the ferrule will swell proportionally to the as surface condensers for condensing exhaust decrease in size of tube and maintain a tight steam in power plants and more particularly to seal at all times. a protecting ferrule for protecting the inlet ends Another object of the invention is to provide an of the tubes of such an apparatus, being particu- 5 improved tube protecting ferrule as specified larly adaptable for use in connection with tubes which may be quickly, easily, and inexpensively which are expanded into the tube sheet. applied, without the use of skilled labor.

The tubes of condensers are connected in fluid With these and other objects in view, as may tight seals with the tube head in a number of appear from the accompanying specification, the ways, such as by the use of packing with ferrules, invention consists of various features of construcexpanding the tube end into the tube receiving tion and combination of parts, which will be first Opening in the ub et and be g or rolli g described in connection with the accompanying the extreme end of the tube. drawings, showing a protecting ferrule for heat In many installations the expanded tube end exchanger tubes of a preferred form embodying with its rolled extreme end is preferable but it the invention, and the features forming the inhas a number of disadvantages among which are vention will be specifically pointed out in the that the expanding and rolling of the tube leave claims.

the inlet end of the tube larger than the diam- In the drawings:

eter of the major length of the tube allowing Figure l is a section through the improved tube coke, stones or other solid foreign matter to enter protecting ferrule showing it in a fragment of a the tube inlet and become lodged in the tube at tube sheet.

the terminus of the expanded portion causing in- Figure 2 is a view partly in edge elevation and terference with the water flow through the tube partly in section of the improved tube protecting and augmenting the erosion and corrosion of the ferrule.

tube. Then also the rolling of the extreme ends Figure 3 is a section on line 3-3 of Figure 2.

of the tubes stresses and strains the metal and Figure 4 is a section of a modified form of the causes crystallization resulting in an early breaktube protecting ferrule showing it in use in a down of the rolled end of the tube with the refragment of atube sheet.

sultant leakage. v Figure 5 is a view partly in edge elevation and The tubes of a surface condenser are made of a partly in section of the modified form of the tube different metal than the tube sheets with the reprotecting ferrule.

sult that during operation of the condenser on Figure 6 is a cross section on line 6-6 of Figelectrolytic action is set up which causes deteriure 5.

oration of the tubes. Referring to the drawings, and more particu- The retubing of a surface condenser is an exlarly to the form of the invention shown in Figpensive operation, as to labor costs, costs of new ures 1 to 3, the improved protective ferrule for tubes and losses due to shut down of the conheat exchanger tubes comprises an annular or denser. ring-like body I which is formed of any suitable It is an object of the present invention to promaterial, preferabl a plastic composition which vide means for connecting condenser or heat ex- 40 is insulating or non-conductive of electrical curchanger tubes to their tube sheets which will emrents and whi Will swell Slightly When W dbody all of the advantages of expanding the tubes e e are a number of ch materi s on the in the tube sheets and will overcome the disadmarket, some manufactured by the akelite C'Orvantages of such construction by preventing the pfl fi and other companies en ag in the entrance of solid foreign matter into the tube manufacture of hard thermmsefltmg pl st cs.

when the foreign matter size is such as to prevent he ann r or r e y l is provided its passage completely through the tube; will with an inwa dly -d s annular r cess 2 eliminate the necessity of rolling the extreme ends eXtBndm-g w y o Its i ner end a d 10mmof the tubes; will provide a firm fluid tight seal ing an annular recess for receiving the end of a between a tube and tube sheet at all times, and .50 condenser or heat exchanger tube as indicated at being of a material which is non-conductive of 3. The inner surface d of the body that forms electricity will prevent electrolytic action between the wall for the bore 5 of the ferrule, tapers outthe tube sheet and tube end, and will also prowardly as it progresses towards the inner side of tect the inlet ends of the tubes from acids and the ferrule so as to form substantially a knife other corroding agents which may be in the water edge, indicated at t, where the extreme inner porcirculated through the condenser. tion of the wall contacts the inner surface of Another advantage of the present invention is the tube 3. that the protective sealing ferrules are made of The tube sheet I of the condenser or heat exmaterial which will swell slightly when it bechanger (not shown) is provided with a bore 8 comes wetted and thus as the tube wears during into which the tube 3 extends and also with a counterbore 9 extending inwardly from the outer face of the tube sheet 1. The tube protecting ferrule I has a driving fit into the counterbore 9, as clearly shown in Figure 1 of the drawings, and when inserted in proper place its outer surface is flush with the outer surface of the tube sheet. The outer perimeter of the annular or ring-like body I is cut away preferably at the innermost corner to form an annular recess in which is sealed a sealing ring ID. The sealing ring In is formed of a hard pressed fibrous material such as compressed wood fiber, paper, or the like, which is more readily susceptible to swelling when wetted than is the material of which the ferrule body I is formed, and when this sealing ring It] becomes wetted it will swell forming a tight seal between the ferrule l and the tube sheet I.

In installing, the tube 3 has its end inserted into the opening 8 in the tube sheet I and the portion of the tube 3 within the opening 8 is expanded in the usual manner to form a fluid tight seal with the tube sheet. However, the tube 3 is of such length that its outermost end terminates short of the outer face of the tube sheet, as clearly shown in Figure 1 of the drawings. Thus the end of the tube extends into the counterbore 9. The ferrule is then placed in the counterbore with the end of the tube in the recessed tube and is driven into place by a sharp blow of a hammer, mallet, or the like. It will be noted that the bore of the ferrule is of less diameter than the bore of the major length of the tube 3 and thus, hard or solid pieces of foreign material of a size too large to pass completely through the tube 3 will be prevented from entering the tube and clogging it. Such entrance and clogging would be permitted without this feature of the ferrule, because in expanding the end of the tube into the tube sheet its internal diameter is slightly increased which would allow foreign particles to enter the expanded end of the tube and become lodged therein due to their inability to pass completely through the tube. By making the body I of electrical current insulating material the tube 3, at its entrance end, will be completely insulated from the tube sheet and thus electrolytic action caused by the fiow of the circulating Water over the two metals in contact, will be eliminated with its resultant deterioration of the tubes. The ferrule being constructed of a hard, compact plastic material will also protect the inlet end of the tube 3 from corrosive and erosive action of chemicals which might be contained in the circulating water. The swelling of the ring l and of the ferrule l are confined within the limits of the counterbore 9. However, as the tube 3 begins to wear or reduce in thickness through long continued use these elements will have a tendency to swell to a greater extent than ordinarily, being released for swelling in a degree equal to the reduction in the thickness of the tube and consequently a tight seal about the tube and tube sheet will be maintained at all times.

Figures l, 5, and 6 show a modified form of the improved ferrule.

In this form the ferrule is formed completely of one piece and comprises the annular or ringlike body 20 which fits into the counterbore 2| in the tube sheet 22 at and surrounding the outer end of the tube receiving opening 23. The annular ring-like body 2!] has an annular recess 24 extending thereinto from its inner side which receives the end of the tube 25. The tube 25 is expanded into the opening 23 and its end projects into the counterbore a sufiicient distance to be firmly engaged within the annular recess 24. The body 20 has a sleeve-like extension 26 formed thereon which projects into the tube 25 beyond the inner edge of the main body 28. The bore 21 of the ferrule 20 is smaller in diameter than the normal major length bore of the tube 25 and the ferrule 20 is also made of material which is nonconductive of electrical currents and which will swell slightly when wetted so that its advantages and actions are the same as those above described in connection with the ferrule I. The sleeve 25 tapers to a knife-like edge 28 at its inner end, as clearly shown in Figures 4 and 5.

It will be understood that the invention is not to be limited to the specific construction or arrangement of parts shown, but that they may be widely modified within the invention defined by the claims.

What is claimed is:

1. A protecting ferrule for the inlet ends of heat exchanger tubes comprising an annular body of hard compact fibrous plastic material which is non-conductive of electrical currents and which will swell slightly when wetted. said annular body having an annular recess extending inwardly from one edge thereof for receiving the .end of a heat exchanger tube, the inner wall of the bore of said annular body tapering outwardly as it approaches the outlet end of the body to provide substantially a knife edge at the outlet end of the body, said annular body having a portion thereof cut away at its outer perimeter to provide an annular space and a sealing ring of hard compact fibrous material capable of swelling when wetted seated in said annular space.

2. The combination with a tube sheet and a tube of a heat exchanger, said tube sheet provided with a tube receiving opening and with a smooth bore counterbore about the outer end of said opening, said tube extending through said opening and partially through said counterbore and being expanded in said opening into fluid tight engagement with the tube sheet, 3. protecting ferrule having a driving fit in said counterbore and provided with an annular recess opening out through its inner end for receiving therein the portion of the tube which projects into said counterbore, said ferrule having its outer surface cut away to provide an annular space, and a sealing ring of hard compact fibrous material capable of swelling when wetted in said annular space and contacting said tube sheet, the diameter of the bore of said protecting ferrule being less than the internal diameter of the tube, said protecting ferrule completely enclosing the outer end of the tube and having its imier surface tapering outwardly as it approaches the outlet end of the ferrule to provide substantially a knife edge at the outlet end of the ferrule.

SAMUEL PENNELLA.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,099,026 Markel Nov. 16, 1937 2,225,615 Bay Dec. 24, 1940 2,252,274 Rossheim Aug. 12, 1941 2,394,402 Pennella Feb. 5, 1946 

